The crime scene was horrific. A poor defenseless elf lay mortally wounded — his head ripped off by a murderer who fled the scene.

"I've been a cop for 20 years, and I've seen a lot of ugly, gruesome scenes, but this was probably the worst," said Shane Ferrari, the undersheriff of New Mexico's San Juan County. The crime scene was his living room.

The victim, an elf named Holly, had been a regular Christmas visitor to the Ferrari residence for years. The lawman feared the killer of Santa's little helper was hiding somewhere in his house.

The culprit later proved to be Josie, the family's 2-year-old Boston terrier.

"As I looked into Josie's eyes, I saw nothing but guilt," Ferrari said. "It was sad."

The undersheriff is bound by oath to uphold the law, he said. He had no choice but to place Josie in custody.

Investigators are looking for surveillance video while Josie is being held under house arrest, without bail, Ferrari said.